Illustrated herein in embodiments are toner processes, and more specifically, emulsion aggregation and coalescence processes. More specifically, disclosed in embodiments are toner compositions and methods for the preparation of a curable toner compositions by a chemical process, such as emulsion aggregation, wherein latex particles, such as latexes containing unsaturated crystalline and/or amorphous polymeric particles such as polyester or sulfonated polyester, are aggregated with a photo initiator, optionally a wax, and optionally a colorant, in the presence of a coagulant such as a polymetal halide or other monovalent or divalent metal coagulants, and thereafter stabilizing the aggregates and coalescing or fusing the aggregates such as by heating the mixture above the resin Tg to provide toner size particles.
Also illustrated herein in embodiments are development processes using such a toner. For example, the toner can be used as a colored toner to print images that are subsequently fused, or the toner can be used as a clear overcoat toner and subsequently cured to provide protection to an underlying colored toner image. The curing, such as ultraviolet curing, can be conducted at the same time as conventional pressure or heated pressure fusing, or it can be conducted in a separate such as subsequent step. The ultraviolet curing desirably crosslinks the unsaturated resin in the toner composition to provide a robust image.
A number of advantages are associated with the toner obtained by the processes and toner compositions illustrated herein. The process allows for particles to be prepared in the size of 3 to 7 microns in diameter with narrow size distributions, such as from about 1.2 to about 1.25, without the use of classifiers. Furthermore, low melting or ultra-low melting fixing temperatures can be obtained by the use of crystalline resins in the toner composition. The aforementioned low fixing temperatures allows for the curing by ultraviolet light to occur at lower temperatures, such as from about 120 to about 135° C. The toner compositions provides improvements for other advantages, such as high temperature document offset properties, such as up to about 85° C., as well as resistance to organic solvents such as methyl ethyl ketone (MEK). This improved document offset means that printed images can withstand such higher temperatures during their lifetime, and can withstand the higher temperatures used in heat sealing processes.